CHRONIC INTERMITTENT HYPOBARIC HYPOXIA AND PULMONARY IMPLICATIONS: AN OCCUPATIONAL RISK FACTOR FOR HIGH-ALTITUDE WORKERS

Saktapov A.K. ¹, Vinnikov D.V. ¹, Ualiyeva A.Y. ¹, Romanova Z.V. ¹,

Aitambayeva N.N. ², Nazarova L.Z. ², Akhanov G.Z. ³, Mukanova O.Z. ⁴

¹Al-Farabi Kazakh National University, Almaty, Kazakhstan

² Kazakhstan’s Medical University “KSPH”, Almaty, Kazakhstan

³Asfendiyarov Kazakh National University, Almaty, Kazakhstan

⁴“Mangystau Central District Hospital” Health Department of Mangystau region, Mangystau region, Kazakhstan

 

Introduction. Chronic intermittent hypobaric hypoxia (CIHH), characteristic of rotational work at high altitude, is a major occupational risk factor for miners, construction workers, and other industrial employees. Alternating cycles of hypoxia and reoxygenation produce physiological stresses distinct from both permanent high-altitude residence and laboratory-induced hypoxia. Despite growing evidence, contradictions persist regarding its long-term pulmonary consequences.

Objective. To synthesize current evidence on the pulmonary effects of CIHH in high-altitude workers and to evaluate preventive strategies for preserving respiratory health.

Materials and Methods. A literature search was conducted in Scopus and Web of Science for the period 2015–2025 using the keywords “chronic intermittent hypobaric hypoxia,” “high altitude,” “pulmonary,” and “respiratory system.” Inclusion criteria comprised original studies, systematic reviews, and meta-analyses.

Results. CIHH consistently induces acute ventilatory responses (hyperventilation, tachypnea, respiratory alkalosis) and reductions in oxygen saturation within the first 48 hours of exposure. Long-term workers demonstrate persistent ventilatory plasticity and partial acclimatization but also recurrent nocturnal desaturation and periodic breathing. Gas exchange efficiency remains impaired, particularly during exertion, with some miners experiencing severe hypoxemia (SpO₂ ≤88%). Echocardiographic studies in Andean cohorts report mild pulmonary hypertension in ~26% of long-term CIHH workers, accompanied by right ventricular remodeling but preserved function. Preventive strategies such as oxygen-enriched rooms and structured acclimatization are variably implemented, more common in Latin America than in Central Asia.

Discussion. CIHH exerts both adaptive and maladaptive effects on the respiratory system. Universal patterns—hyperventilation, desaturation, and sleep-disordered breathing—are documented across regions, although the prevalence of long-term complications varies, partly due to the “healthy worker effect” in Central Asia. Current evidence is limited by small sample sizes, observational designs, and reliance on animal models. These discrepancies highlight the need for standardized monitoring and multinational comparative research.

Conclusion. CIHH is a significant occupational hazard that induces ventilatory strain, sleep-related breathing disturbances, and pulmonary vascular remodeling. While most workers adapt, a subset develops subclinical pulmonary hypertension and lasting respiratory impairment. Large prospective studies and harmonized preventive strategies—including acclimatization, monitoring, and oxygen support—are essential to protect high-altitude workers.

Keywords: chronic intermittent hypobaric hypoxia, high altitude, pulmonary, respiratory system.

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